This invention specifically relates to holding dialysis bag for adding and removing samples in biochemical and immunochemical studies.
In biochemical processes such as extraction, purification, conjugation and characterization excess reagents are removed from desired molecules by dialysis. To perform dialysis, a sample is taken in a bag with semipermeable membrane and stirred against buffer. With time, large molecules are retained inside the bag while small reagent molecules diffuse into buffer surrounding the bag. This selective retention of molecules is due to the presence of pores in the membrane of bag.
Prior to adding sample, one end of the dialysis tube is closed tightly either by putting a knot with twine or by using a clamp so that no liquid leaks. The first problem at this stage is holding the extremely thin and highly flexible bag erect so that liquid sample can be added. Ordinarily, a small portion at the top of bag is held in between a finger and thumb. Then, the bag is open and sample is added with a pipette. Most accidents happen at this point. Because attention is divided between holding the bag and adding sample, because one wears gloves and because membrane is extremely thin, hold on the dialysis bag becomes weak. A slip of the bag causes loss of valuable sample. If sample contains radioactive compounds, therapeutic drugs, toxins and other similar cytotoxic biologicals, surface contamination requires a cleanup.
The volume of sample for dialysis varies from time to time. For a sample of small volume, a pipette is used to add to dialysis bag. However, when sample volume is large, the second problem arises. Generally, this problem is addressed by using a funnel and a ring stand. The stem of funnel is inserted into the bag, held together tightly and then, sample is poured. Under the weight of added sample, the bag tends to slip from the hold. Therefore, the rest of the bag also needs support. Improper support makes the bag exert a downward pull causing, first slip and then spill of valuable sample. This method is cumbersome and the bag still needs support.
After adding sample, the bag is closed with twine or clamp. This step requires open access. The third problem arises at this step. Since the volume of sample and the height of bag vary, proper support and access is not always available. Commonly, the top of bag is held with fingers of one hand and the clamp is applied with the other hand. To close with twine, both hands are needed to tie a proper knot. This requires right kind of support with proper access to the bag. Alternately, help is needed from another person. Improper access for closing the bag, therefore, leads to potential risk of spilling the sample.
After closing, the bag is tested for leaks by gently squeezing, and then, dialyzed against suitable buffer. At the end of dialysis, sample is collected from the bag. The fourth problem arises at this stage. To collect dialyzed sample, first, the bag is held vertical and then, clamp is removed. If twine is used, the bag is cut slightly below the knot at the top. At this phase the bag definitely needs proper support to prevent from collapsing. Needless to say that support should also provide free and open access to the bag so that sample can be collected, properly. After collecting sample, empty bag is discarded.
In brief, giving proper support and holding securely in place are crucial not only for adding but also for collecting sample from the dialysis bag. Also, providing open access is essential for closing the bag before dialysis and for collecting the sample after dialysis. Providing a funnel where it is required greatly helps in adding large volume of sample to the dialysis bag.
The objects and advantages of this invention are:
(a) to fabricate a cradle from a tube so that dialysis bag can be held safely in place PA1 (b) to provide a bottom plate for holding cradle tube firmly PA1 (c) to attach cradle tube at an angle so that dialysis bag stays in place and also retains liquid sample without spilling PA1 (d) to provide quick and open access to dialysis bag PA1 (e) to furnish a cup at the bottom of cradle so that any sample spilled by accident can be saved PA1 (f) to provide additional support in the back of cradle tube PA1 (g) to provide a top plate with a hole for seating a funnel without needing a separate ring stand PA1 (h) to fabricate bottom, vertical and top plates from one piece of material without requiring the manufacturer use nuts and bolts PA1 (i) to provide transparency so that level of sample and the status of bag can be viewed clearly, and PA1 (j) to fabricate the unit from commonly available materials which are hard, durable and tough to break
Further objects and advantages will be apparent from the following description and drawings.